This invention relates to a system for paying off lengths of elongated product from a rotatable coiled supply. More particularly, the invention relates to a system for paying off lengths of small diameter tubing from a rotatable heavy coiled package containing about two miles of such tubing.
In providing lengths of thin walled air conditioning tubing to a hairpin bending machine, for example, it is imperative that the tubing be provided undamaged on a highly consistent basis. Damaged tubing can interfere with production and it can lead to failure of the tubing in service.
Dispensing undamaged lengths of aluminum tubing to a work area of a bending machine or other processing means can produce more difficulties than dispensing a solid product such as wire, for example, because the aluminum tubing is more susceptible to damage which can result in its rejection. For instance, the tubing can be rejected for being merely out of round, that is, no longer circular in cross section. Obviously, a solid product such as wire is resistant to forces, e.g. compressive forces, which would damage thin walled tubing. Thus, it can be seen that a system suitable for dispensing a solid product, for example, wire, may not be suitable for dispensing thin walled tubing because of the damage problems involved.
The thin walled aluminum tubing referred to is susceptible to damage in many ways, especially in view of the large coiled packages referred to above (desirable from an economic point of view) from which it is dispensed. For example, the tubing can be damaged when it is used as a means to rotate the coiled package to pay off lengths to the aforementioned bending machine. This damage comes about by having the outer winding of tubing on which the pull is exerted being forced or pulled into the inner windings. In this situation, tubing from the outer winding tends to abraid tubing in the inner windings thereby causing damage to it. Also there is a great likelihood of the tubing from the outer winding becoming stuck in the inner windings often requiring a greater pulling force than normal to rotate the coiled supply. Exerting this greater force to free the outer windings can buckle or kink or even break the tubing. Thus it can be seen that thin walled tubing can easily be damaged as a result of the outer windings becoming embedded in the inner windings. In addition to the problem of damaging the immediate tubing, the uniformity of the windings in the coiled supply can be disoriented, interfering with smooth, subsequent dispensing of the tubing.
An obvious expedient to avoid these problems would be a motor-driven mechanism which would rotate these large coiled packages to provide tubing at a rate commensurate with that required by the bending machine. However, that type of mechanism greatly complicates the process, adds to its cost and, in reality, negates the economic benefits derived from the use of these large coiled packages of tubing. For these reasons, such a mechanism is undesirable.